Before there were automatic single deck card shufflers, casinos had card dealers hand shuffle cards for games played with a single deck, such as poker. Once in a while between hands, the dealer would also have to count the deck to make sure the number of cards in the deck was still correct. When the decks are no longer needed for a particular game, the game breaks, or a new setup is brought in, two new decks, a casino employee would have to do a setup, put the cards back in original order, so the cards can be spread and checked at the start of the next game. Doing a setup putting a scrambled deck back in its original order, is something casinos still have to do by hand.
The method of shuffling most often used by professional poker dealers is a five step process referred to as scramble, riffle, riffle, strip, riffle. A scramble is when a deck of cards is spread out face down on the table by the dealer and then randomly mixed around together by the dealer using both hands in a circular motion. The cards and then gathered together into a pile, picked up, and straightened out into a deck again. Some casinos, for expediency, have eliminated the scramble.
In the second step the riffle, or dovetail shuffle, a deck of cards is first cut about midway into two half decks. Cards from the two half decks are then riffled, or interlaced, together again to form one deck. This process is repeated a second time. The next step is known as the strip, or box. The dealer holds the deck and removes approximately the top quarter of the deck and places it on the table. The dealer then removes the next group of cards, about a quarter of a full deck, and places this second group of cards on top of the first group of cards already on the table. This is repeated again, with the dealer placing a third group of cards, about one quarter of the deck, on top of the second group of cards. The last remaining group of cards, the bottom quarter of the deck, is then placed on top of the cards on the table. Essentially, the deck is divided into four parts, and the parts put in inverse order. After the strip or box, the dealer does another riffle to complete the shuffle. The deck is then ready to cut and deal.
Another method of shuffling, which results in a mathematically provable random shuffle, would be for a dealer to simply do seven riffle shuffles, instead of the standard riffle, riffle, strip, riffle. This is not done in casinos as it would be time consuming. The random outcome of this method was proven through mathematical modeling by David Bayer and Persi Diaconis, in their paper “Trailing the Dovetail Shuffle to Its Lair” (Ann. Appl. Probability 2, 294-313, 1992). They showed that after seven random riffle shuffles, of a deck of 52 cards, every configuration or outcome is possible and nearly equally likely, and that more shuffles would not increase the degree of randomness in the deck. The mathematical model of the riffle shuffle they used is called the GSR (Gilbert, Shannon, Reeds) model. Following the publication of that paper, much research was done by others to investigate the same question using different methods. The subsequent research proved the validity of the GSR model and the conclusions of Bayer and Diaconis.
The device of the current invention can shuffle a deck of cards in either manor. It can do the industry standard acceptable riffle, riffle, strip, riffle, or it can do the mathematically proven seven riffles. It can also cut the deck, count the deck, verify that there is one and only one of each card, and do a setup.